Projects that aren't meant to generate a wheel and `pyproject.toml`

One thing I would specifically caution people about is that “unblock PEP 723” is explicitly not a requirement here. I very much want to see script dependency metadata standardised, but I won’t let that desire get in the way of making the right decision here. For example, if [run] turns out not to be the appropriate section name, then sorry PEP 723, you made the wrong guess and you need to change. Conversely, arguments that [run] should be used “because it’s what PEP 723 specified” aren’t valid - justify the choice on its own merits please.